Endoluminal vascular prosthesis

ABSTRACT

Disclosed is a tubular endoluminal vascular prosthesis, useful in treating, for example, an abdominal aortic aneurysm. The prosthesis includes a self expandable wire support structure surrounded by a flexible tubular membrane. A delivery catheter and methods are also disclosed.

BACKGROUND OF THE INVENTION

The present invention relates to endoluminal vascular prostheses, and,in one application, to self-expanding endoluminal vascular prosthesesfor use in the treatment of abdominal aortic aneurysms.

An abdominal aortic aneurysm is a sac caused by an abnormal dilation ofthe wall of the aorta, a major artery of the body, as it passes throughthe abdomen. The abdomen is that portion of the body which lies betweenthe thorax and the pelvis. It contains a cavity, known as the abdominalcavity, separated by the diaphragm from the thoracic cavity and linedwith a serous membrane, the peritoneum. The aorta is the main trunk, orartery, from which the systemic arterial system proceeds. It arises fromthe left ventricle of the heart, passes upward, bends over and passesdown through the thorax and through the abdomen to about the level ofthe fourth lumbar vertebra, where it divides into the two common iliacarteries.

The aneurysm usually arises in the infrarenal portion of the diseasedaorta, for example, below the kidneys. When left untreated, the aneurysmmay eventually cause rupture of the sac with ensuing fatal hemorrhagingin a very short time. High mortality associated with the rupture ledinitially to transabdominal surgical repair of abdominal aorticaneurysms. Surgery involving the abdominal wall, however, is a majorundertaking with associated high risks. There is considerable mortalityand morbidity associated with this magnitude of surgical intervention,which in essence involves replacing the diseased and aneurysmal segmentof blood vessel with a prosthetic device which typically is a synthetictube, or graft, usually fabricated of Polyester, Urethane, DACRON®,TEFLON®, or other suitable material.

To perform the surgical procedure requires exposure of the aorta throughan abdominal incision which can extend from the rib cage to the pubis.The aorta must be closed both above and below the aneurysm, so that theaneurysm can then be opened and the thrombus, or blood clot, andarteriosclerotic debris removed. Small arterial branches from the backwall of the aorta are tied off. The DACRON® tube, or graft, ofapproximately the same size of the normal aorta is sutured in place,thereby replacing the aneurysm. Blood flow is then reestablished throughthe graft. It is necessary to move the intestines in order to get to theback wall of the abdomen prior to clamping off the aorta.

If the surgery is performed prior to rupturing of the abdominal aorticaneurysm, the survival rate of treated patients is markedly higher thanif the surgery is performed after the aneurysm ruptures, although themortality rate is still quite high. If the surgery is performed prior tothe aneurysm rupturing, the mortality rate is typically slightly lessthan 10%. Conventional surgery performed after the rupture of theaneurysm is significantly higher, one study reporting a mortality rateof 66.5%. Although abdominal aortic aneurysms can be detected fromroutine examinations, the patient does not experience any pain from thecondition. Thus, if the patient is not receiving routine examinations,it is possible that the aneurysm will progress to the rupture stage,wherein the mortality rates are significantly higher.

Disadvantages associated with the conventional, prior art surgery, inaddition to the high mortality rate include the extended recovery periodassociated with such surgery; difficulties in suturing the graft, ortube, to the aorta; the loss of the existing aorta wall and thrombosisto support and reinforce the graft; the unsuitability of the surgery formany patients having abdominal aortic aneurysms; and the problemsassociated with performing the surgery on an emergency basis after theaneurysm has ruptured. A patient can expect to spend from one to twoweeks in the hospital after the surgery, a major portion of which isspent in the intensive care unit, and a convalescence period at homefrom two to three months, particularly if the patient has otherillnesses such as heart, lung, liver, and/or kidney disease, in whichcase the hospital stay is also lengthened. Since the graft must besecured, or sutured, to the remaining portion of the aorta, it is manytimes difficult to perform the suturing step because the thrombosispresent on the remaining portion of the aorta, and that remainingportion of the aorta wall may many times be friable, or easily crumbled.

Since many patients having abdominal aortic aneurysms have other chronicillnesses, such as heart, lung, liver, and/or kidney disease, coupledwith the fact that many of these patients are older, the average agebeing approximately 67 years old, these patients are not idealcandidates for such major surgery.

More recently, a significantly less invasive clinical approach toaneurysm repair, known as endovascular grafting, has been developed.Parodi, et al. provide one of the first clinical descriptions of thistherapy. Parodi, J. C., et al., “Transfemoral Intraluminal GraftImplantation for Abdominal Aortic Aneurysms,” 5 Annals of VascularSurgery 491 (1991). Endovascular grafting involves the transluminalplacement of a prosthetic arterial graft within the lumen of the artery.

In general, transluminally implantable prostheses adapted for use in theabdominal aorta comprise a tubular wire cage surrounded by a tubularPTFE or Dacron sleeve. Both balloon expandable and self expandablesupport structures have been proposed. Endovascular grafts adapted totreat both straight segment and bifurcation aneurysms have also beenproposed.

Notwithstanding the foregoing, there remains a need for a structurallysimple, easily deployable transluminally implantable endovascularprosthesis, with a support structure adaptable to span either a straightor bifurcated abdominal aortic aneurysm. Preferably, the tubularprosthesis can be self expanded at the site to treat the abdominalaortic aneurysm, and exhibits flexibility to accommodate nonlinearanatomies and normal anatomical movement.

SUMMARY OF THE INVENTION

There is provided in accordance with one aspect of the presentinvention, a moveable link for securing two portions of the wall of atubular endovascular prosthesis. The link comprises a first wire portionhaving two side-by-side legs extending in a first direction and an apexthereon. A second wire portion is positioned adjacent the first wireportion. The first wire portion is wrapped around the second wireportion so that at least a portion of the apex faces in the firstdirection to at least partially entrap the second wire portion.

In accordance with another aspect of the present invention, there isprovided an endoluminal prosthesis. The prosthesis comprises a tubularwire support having a proximal end, a distal end and a central lumenextending therethrough. The wire support comprises at least a first anda second axially adjacent tubular segments, joined by at least onefolded link extending therebetween. The first and second segments andthe link are preferably formed from a single length of wire.

Preferably, at least three folded links are provided between the firstand second segments. The wire in each segment preferably comprises aseries of proximal bends, a series of distal bends, creating a series ofstrut segments connecting the proximal bends and the distal bends toform a tubular segment wall. The folded link comprises a proximal ordistal bend, together with a portion of two struts joined by the bend,extending through the loop formed by the other of the proximal anddistal bends, to moveably link adjacent segments.

In accordance with a further aspect of the present invention, there isprovided a method of making an endoluminal prosthesis. The methodcomprises the steps of providing a length of wire, and forming the wireinto two or more zig-zag sections having proximal and distal apexes. Theformed wire is rolled about an axis to produce two or more tubularelements positioned along the axis such that at least one proximal apexon one section axially overlaps with a distal apex on a second section.One of the proximal apex and distal apex is folded through the other ofthe proximal apex and the distal apex to produce a folded link.Preferably, the method further comprises the step of positioning atubular polymeric sleeve concentrically on at least one of the tubularelements. In one embodiment, the tubular polymeric sleeve comprisesPTFE.

In accordance with another aspect of the present invention, there isprovided an endoluminal prosthesis. The prosthesis comprises an elongateflexible wire, formed into a plurality of axially adjacent tubularsegments spaced along an axis, each tubular segment comprising a zig-zagsection of the wire, having a plurality of proximal bends and distalbends. The wire continues between each adjacent tubular segment. Atleast two side-by-side wire segments joined by a first bend on a firsttubular element extend through and interlock around a portion of asecond tubular segment to provide a moveable link. The prosthesis isradially compressible into a first, reduced cross-section forimplantation into a body lumen, and self expandable to a second,enlarged cross-sectional configuration at a treatment site in a bodylumen.

Preferably, the prosthesis further comprises an outer tubular sleevesurrounding at least a portion of the prosthesis. Preferably, at leastthree segments are formed from the wire. The prosthesis has an expansionratio of at least about 1:4, and an expanded diameter of at least about20 mm to 30 mm in an unconstrained expansion.

Preferably, each axially adjacent pair of segments is characterized byan interface therebetween, wherein at least some of the proximal bendson one segment align with distal bends on the other segment to providean opposing apex pair, and at least 30% of the apex pairs in a giveninterface are interlocked.

Further features and advantages of the present invention will becomeapparent to those of ordinary skill in the art in view of the disclosureherein, when considered together with the attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a straight segment vascularprosthesis in accordance with the present invention, positioned within asymmetric abdominal aortic aneurysm.

FIG. 2 is an exploded view of an endoluminal vascular prosthesis inaccordance with the present invention, showing a self expandable wiresupport structure separated from an outer tubular sleeve.

FIG. 3 is a plan view of a formed wire useful for rolling about an axisinto a multi-segment support structure in accordance with the presentinvention.

FIG. 4 is an enlarged detail view of a portion of the formed wireillustrated in FIG. 3.

FIG. 5 is a schematic view of a portion of a wire cage wall,illustrating folded link connections between adjacent apexes.

FIG. 6 is an exploded view of two opposing apexes dimensioned for oneembodiment of the folded link connection of the present invention.

FIG. 7 is an enlarged view of a folded link, taken along the lines 7—7in FIG. 5.

FIG. 8 is a cross-sectional view taken along the line 8—8 in FIG. 7.

FIGS. 6A, 7A, 8A, 7B, 8B, 7C, and 7D illustrate alternate embodiments ofa folded link constructed from an opposing apex pair.

FIG. 9 is a partial view of a junction between two adjacent tubularsegments, illustrating oppositely oriented folded links in accordancewith the present invention.

FIG. 10 is a cross-section taken along the line 10—10 in FIG. 9.

FIG. 11 is a schematic view of a portion of a wall of a graft, laid outflat, illustrating an alternating folded link pattern.

FIG. 12 is a wall pattern as in FIG. 11, illustrating a multi-zonefolded link pattern.

FIGS. 12A through 12C illustrate an alternate wall pattern, whichpermits axially staggered links between adjacent graft segments.

FIG. 13 is a schematic illustration of a straight segment deliverycatheter in accordance with the present invention, positioned within anabdominal aortic aneurysm.

FIG. 14 is an illustration as in FIG. 13, with the straight segmentendoluminal prosthesis partially deployed from the delivery catheter.

FIG. 15 is a schematic representation of the abdominal aortic anatomy,with an endoluminal vascular prostheses of the present inventionpositioned within each of the right renal artery and the right commoniliac.

FIG. 16 is a schematic representation of a straight segment graft inaccordance with a further embodiment of the present invention, with sideopenings to permit renal perfusion.

FIG. 17 is a schematic representation of a bifurcated vascularprosthesis in accordance with the present invention, positioned at thebifurcation between the abdominal aorta and the right and left commoniliac arteries.

FIG. 18 is a cross-sectional view of the implanted graft taken along thelines 18—18 of FIG. 17.

FIG. 19 is an exploded view of the bifurcated vascular prosthesis inaccordance with the present invention, showing a two-part selfexpandable wire support structure separated from an outer tubularsleeve.

FIG. 20 is a plan view of formed wire useful for rolling about an axisinto an aortic trunk segment and a first iliac branch segment supportstructure in accordance with the present invention.

FIG. 21 is side elevational cross-section of a bifurcation graftdelivery catheter in accordance with the present invention.

FIG. 22 is an enlargement of the portion delineated by the line 22—22 inFIG. 21.

FIG. 23 is a cross-section taken along the line 23—23 in FIG. 22.

FIG. 24 is a cross-section taken along the line 24—24 in FIG. 22.

FIG. 25 is a schematic representation of a bifurcated graft deploymentcatheter of the present invention, positioned within the ipsilateraliliac and the aorta, with the contralateral guidewire positioned withinthe contralateral iliac.

FIG. 26 is a schematic representation as in FIG. 25, with the outersheath proximally retracted and the compressed iliac branches of thegraft moving into position within the iliac arteries.

FIG. 27 is a schematic representation as in FIG. 26, with the compressediliac branches of the graft within the iliac arteries, and the mainaortic trunk of the graft deployed within the aorta.

FIG. 28 is a schematic representation as in FIG. 27, with thecontralateral iliac branch of the graft deployed.

FIG. 29 is a schematic representation as in FIG. 28, followingdeployment of the ipsilateral branch of the graft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, there is disclosed a schematic representation ofthe abdominal part of the aorta and its principal branches. Inparticular, the abdominal aorta 30 is characterized by a right renalartery 32 and left renal artery 34. The large terminal branches of theaorta are the right and left common iliac arteries 36 and 38. Additionalvessels (e.g., second lumbar, testicular, inferior mesenteric, middlesacral) have been omitted for simplification. A generally symmetricalaneurysm 40 is illustrated in the infrarenal portion of the diseasedaorta. An expanded straight segment endoluminal vascular prosthesis 42,in accordance with the present invention, is illustrated spanning theaneurysm 40.

The endoluminal vascular prosthesis 42 includes a polymeric sleeve 44and a tubular wire support 46, which are illustrated in situ in FIG. 1.The sleeve 44 and wire support 46 are more readily visualized in theexploded view shown in FIG. 2. The endoluminal prosthesis 42 illustratedand described herein depicts an embodiment in which the polymeric sleeve44 is situated concentrically outside of the tubular wire support 46.However, other embodiments may include a sleeve situated insteadconcentrically inside the wire support or on both of the inside and theoutside of the wire support. Alternatively, the wire support may beembedded within a polymeric matrix which makes up the sleeve. Regardlessof whether the sleeve 44 is inside or outside the wire support 46, thesleeve may be attached to the wire support by any of a variety of means,including laser bonding, adhesives, clips, sutures, dipping or sprayingor others, depending upon the composition of the sleeve 44 and overallgraft design.

The polymeric sleeve 44 may be formed from any of a variety of syntheticpolymeric materials, or combinations thereof, including PTFE, PE, PET,Urethane, Dacron, nylon, polyester or woven textiles. Preferably, thesleeve material exhibits relatively low inherent elasticity, or lowelasticity out to the intended enlarged diameter of the wire cage 46.The sleeve material preferably has a thin profile, such as no largerthan about 0.002 inches to about 0.005 inches.

In a preferred embodiment of the invention, the material of sleeve 44 issufficiently porous to permit ingrowth of endothelial cells, therebyproviding more secure anchorage of the prosthesis and potentiallyreducing flow resistance, sheer forces, and leakage of blood around theprosthesis. Porosity in polymeric sleeve materials may be estimated bymeasuring water permeability as a function of hydrostatic pressure,which will preferably range from about 3 to 6 psi.

The porosity characteristics of the polymeric sleeve 44 may be eitherhomogeneous throughout the axial length of the prosthesis 42, or mayvary according to the axial position along the prosthesis 42. Forexample, referring to FIGS. 1 and 2, different physical properties willbe called upon at different axial positions along the prosthesis 42 inuse. At least a proximal portion 55 and a distal portion 59 of theprosthesis 42 will seat against the native vessel wall, proximally anddistally of the aneurysm. In these proximal and distal portions, theprosthesis preferably encourages endothelial growth, or, at least,permits endothelial growth to infiltrate portions of the prosthesis inorder to enhance anchoring and minimize leakage. A central portion 57 ofthe prosthesis spans the aneurysm, and anchoring is less of an issue.Instead, maximizing lumen diameter and minimizing blood flow through theprosthesis wall become primary objectives. Thus, in a central zone 57 ofthe prosthesis 42, the polymeric sleeve 44 may either be nonporous, orprovided with pores of relatively lower porosity

A multi-zoned prosthesis 42 may also be provided in accordance with thepresent invention by positioning a tubular sleeve 44 on a centralportion 57 of the prosthesis, such that it spans the aneurysm to betreated, but leaving a proximal attachment zone 55 and a distalattachment zone 59 of the prosthesis 42 having exposed wires from thewire support 46. In this embodiment, the exposed wires 46 are positionedin contact with the vessel wall both proximally and distally of theaneurysm, such that the wire, over time, may become embedded in cellgrowth on the interior surface of the vessel wall.

In one embodiment of the prosthesis 42, the sleeve 44 and/or the wiresupport 46 is tapered, having a relatively larger expanded diameter atthe proximal end 50 compared to the distal end 52. The tapered designmay allow the prosthesis to conform better to the natural decreasingdistal cross-section of the vessel, to reduce the risk of graftmigration and potentially create better flow dynamics. The cage 46 canbe provided with a proximal zone 55 and distal zone 59 that have alarger average expanded diameter than the central zone 57, asillustrated in FIG. 2. This configuration may desirably resist migrationof the prosthesis within the vessel and reduce leakage around the endsof the prosthesis.

The tubular wire support 46 is preferably formed from a continuoussingle length of round or flattened wire. Alternatively, two or morewire lengths can be secured together to produce the wire support 46. Thewire support 46 is preferably formed in a plurality of discrete tubularsegments 54, connected together and oriented about a common axis. Eachpair of adjacent segments 54 is connected by a connector 66 as will bediscussed. The connectors 66 collectively produce a generally axiallyextending backbone which adds axial strength to the prosthesis 42.Adjacent segments can be connected both by the backbone, as well as theinterlocking junction disclosed below. Additional structures, includingcircumferentially extending sutures, solder joints, and wire loops mayalso be used.

The segmented configuration of the tubular wire support 46 facilitates agreat deal of flexibility. Each segment 54, though joined to adjacentsegments, may be independently engineered to yield desired parameters.Each segment may range in axial length from about 0.3 to about 5 cm.Generally, the shorter their length the greater the radial strength. Anendoluminal prosthesis may include from about 1 to about 50 segments,preferably from about 3 to about 10 segments. For example, while a shortgraft patch, in accordance with the invention, may comprise only 2segments and span a total of 2 to 3 cm, a complete graft may comprise 4or more segments and span the entire aortic aneurysm. In addition to theflexibility and other functional benefits available through employmentof different length segments, further flexibility can be achievedthrough adjustments in the number, angle, or configuration of the wirebends associated with the tubular support.

In addition to having differing expanded diameters in different zones ofthe prosthesis 42, different zones can be provided with a differentradial expansion force, such as ranging from about 0.2 lbs to about 0.8lbs. In one embodiment, the proximal zone 55 is provided with a greaterradial force than the central zone 57 and/or distal zone 59. The greaterradial force can be provided in any of a variety of manners discussedelsewhere herein, such as through the use of an additional one or two orthree or more proximal bends 60, distal bends 62 and wall sections 64compared to a reference segment 54 in the central zone 57 or distal zone59. Alternatively, additional spring force can be achieved in theproximal zone 55 through the use of the same number of proximal bends 60as in the rest of the prosthesis, but with a heavier gauge wire.

The wire may be made from any of a variety of different alloys, such aselgiloy, nitinol or MP35N, or other alloys which include nickel,titanium, tantalum, or stainless steel, high Co—Cr alloys or othertemperature sensitive materials. For example, an alloy comprising Ni15%, Co 40%, Cr 20%, Mo 7% and balance Fe may be used. The tensilestrength of suitable wire is generally above about 300 Ksi and oftenbetween about 300 and about 340 Ksi for many embodiments. In oneembodiment, a Chromium-Nickel-Molybdenum alloy such as that marketedunder the name Conichrom (Fort Wayne Metals, Indiana) has a tensilestrength ranging from 300 to 320 K psi, elongation of 3.5-4.0%. The wiremay be treated with a plasma coating and be provided with or withoutadditional coatings such as PTFE, Teflon, Perlyne and drugs.

In addition to segment length and bend configuration, discussed above,another determinant of radial strength is wire gauge. The radialstrength, measured at 50% of the collapsed profile, preferably rangesfrom about 0.2 lb to 0.8 lb, and generally from about 0.4 lb to about0.5 lb. or more. Preferred wire diameters in accordance with the presentinvention range from about 0.004 inches to about 0.020 inches. Morepreferably, the wire diameters range from about 0.006 inches to about0.018 inches. In general, the greater the wire diameter, the greater theradial strength for a given wire layout. Thus, the wire gauge can bevaried depending upon the application of the finished graft, incombination with/or separate from variation in other design parameters(such as the number of struts, or proximal bends 60 and distal bends 62per segment), as will be discussed. A wire diameter of approximately0.018 inches may be useful in a graft having four segments each having2.5 cm length per segment, each segment having six struts intended foruse in the aorta, while a smaller diameter such as 0.006 inches might beuseful for a 0.5 cm segment graft having 5 struts per segment intendedfor the iliac artery. The length of cage 42 could be as long as about 28cm.

In one embodiment of the present invention, the wire diameter is taperedfrom the proximal to distal ends. Alternatively, the wire diameter maybe tapered incrementally or stepped down, or stepped up, depending ondiffering radial strength requirements along the length of the graft foreach particular clinical application. In one embodiment, intended forthe abdominal aortic artery, the wire has a cross-section of about 0.018inches in the proximal zone 55 and the wire tapers down to a diameter ofabout 0.006 inches in the distal zone 59 of the graft 42. End pointdimensions and rates of taper can be varied widely, within the spirit ofthe present invention, depending upon the desired clinical performance.

Referring to FIG. 3, there is illustrated a plan view of a single formedwire used for rolling about a longitudinal axis to produce a foursegment straight tubular wire support. The formed wire exhibits distinctsegments, each corresponding to an individual tubular segment 54 in thetubular support (see FIGS. 1 and 2).

Each segment has a repeating pattern of proximal bends 60 connected tocorresponding distal bends 62 by wall sections 64 which extend in agenerally zig zag configuration when the segment 54 is radiallyexpanded. Each segment 54 is connected to the adjacent segment 54through a connector 66, except at the terminal ends of the graft. Theconnector 66 in the illustrated embodiment comprises two wall sections64 which connect a proximal bend 60 on a first segment 54 with a distalbend 62 on a second, adjacent segment 54. The connector 66 mayadditionally be provided with a connector bend 68, which may be used toimpart increased radial strength to the graft and/or provide a tic sitefor a circumferentially extending suture.

Referring to FIG. 4, there is shown an enlarged view of the wire supportillustrating a connector 66 portion between adjacent segments 54. In theembodiment shown in FIG. 4, a proximal bend 60 comprises about a 180degree arc, having a radial diameter of (w) (Ranging from 0.070 to 0.009inches), depending on wire diameter followed by a relatively shortlength of parallel wire spanning an axial distance of d1. The parallelwires thereafter diverge outwardly from one another and form the strutsections 64, or the proximal half of a connector 66. At the distal endof the strut sections 64, the wire forms a distal bend 62, preferablyhaving identical characteristics as the proximal bend 60, except beingconcave in the opposite direction. The axial direction component of thedistance between the apices of the corresponding proximal and distalbends 60, 62 on a given strut section 64 is referred to as (d) andrepresents the axial length of that segment. The total expanded angledefined by the bend 60 and the divergent strut sections 64 isrepresented by α. Upon compression to a collapsed state, such as whenthe graft is within the deployment catheter, the angle α is reduced toα′. In the expanded configuration, α is generally within the range offrom about 35° to about 45° for a six apex section having an axiallength of about 1.5 cm or 2 cm and a diameter of about 25 mm or 28 mm.The expanded circumferential distance between any two adjacent distalbends 62 (or proximal bends 60) is defined as (s).

In general, the diameter W of each proximal bend 60 or distal bend 62 iswithin the range of from about 0.009 inches to about 0.070 inchesdepending upon the wire diameter. Diameter W is preferably as small aspossible for a given wire diameter and wire characteristics. As will beappreciated by those of skill in the art, as the distance W is reducedto approach two times the cross-section of the wire, the bend 60 or 62will exceed the elastic limit of the wire, and radial strength of thefinished segment will be lost. Determination of a minimum value for W,in the context of a particular wire diameter and wire material, can bereadily determined through routine experimentation by those of skill inthe art.

As will be appreciated from FIGS. 3 and 4, the sum of the distances (s)in a plane transverse to the longitudinal axis of the finished graftwill correspond to the circumference of the finished graft cage in thatplane. For a given circumference, the number of proximal bends 60 ordistal bends 62 is directly related to the distance (s) in thecorresponding plane. Preferably, the finished graft in any singletransverse plane will have from about 3 to about 10 (s) dimensions,preferably from about 4 to about 8 (s) dimensions and, more preferably,about 5 or 6 (s) dimensions for an aortic application. Each (s)dimension corresponds to the distance between any two adjacent bends60-60 or 62-62 as will be apparent from the discussion herein. Eachsegment 54 can thus be visualized as a series of triangles extendingcircumferentially around the axis of the graft, defined by a proximalbend 60 and two distal bends 62 or the reverse.

In one embodiment of the type illustrated in FIG. 4, w is about 2.0 mm±1mm for a 0.018 inch wire diameter. D1 is about 3 mm±1 mm, and d is about20 mm±1 mm. Specific dimensions for all of the foregoing variables canbe varied considerably, depending upon the desired wire configuration,in view of the disclosure herein.

Referring to FIGS. 5 and 6, one or more apexes 76 is provided with anelongated axial length d2, which permits the apex 76 to be wrappedaround a corresponding portion 78 such as an apex of the adjacentsegment to provide an interlocking link 70 between two axially adjacentcage segments. In one embodiment of the link 70 produced by the opposingapexes 76 and 78 of FIG. 6, utilizing wire having a diameter from 0.012″to 0.018″, d1 is generally within the range of from about 1 mm to about4 mm and d2 is within the range of from about 5 mm to about 9 mm. Ingeneral, a longer d2 dimension permits accommodation for greater axialtravel of apex 78 with respect to 76, as will be discussed, therebypermitting greater lateral flexibility of the graft. W1 is within therange of from about 3 mm to about 5 mm, and W2 is sufficiently less thanW1 that the apex 76 can fit within the apex 78. Any of a wide variety ofspecific apex configurations and dimensions can be utilized, as will beapparent to those of skill in the art in view of the disclosure herein.Regardless of the specific dimensions, the end of the apex 76 isadvanced through the apex 78, and folded back upon its self to hook theapex 78 therein to provide a link 70 in accordance with the presentinvention.

The resulting link 70 (see FIGS. 7 and 8) comprises a wall portion 71extending in a first direction, substantially parallel to the axis ofthe graft, and a transverse portion 72 extending transverse to the axisof the graft. A return portion 73 extends generally in the oppositedirection from the wall portion 71 to create a generally “U” shapedhook. In certain embodiments, a closing portion 74 is also provided, tominimize the risk of excessive axial compression of the wire cage. Theforgoing structure produces a functionally closed aperture 77, whichreceives the interlocking section 75 of the adjacent graft segment.Alternatively, see FIG. 10.

In general, the aperture 77 preferably has a width (as viewed in FIG. 8)in the radial graft direction of substantially equal to the radialdirection dimension of the interlocking section 75. In this embodiment,the interlocking section 75, as well as the locking portion 71 andreturn portion 73 can be flattened in the radial direction, to minimizethe transverse cross-section of the link 70. In the axial direction, theaperture 77 is preferably greater than the axial direction dimension ofthe interlocking section 75, to accommodate some axial movement of eachadjoining tubular segment of the graft. The axial length of the aperture77 is at least about 2 times, and preferably at least about 3 or 4 timesthe cross-section of the interlocking section 75. The optimum axiallength of the aperture 77 can be determined through routineexperimentation by one of skill in the art in view of the intendedclinical performance, taking into account the number of links 70 pertransverse plane as well as the desired curvature of the finished graft.

FIGS. 6A, 7A and 8A illustrate an alternate configuration for themoveable link 70. With this configuration, the radial expansion forcewill be higher.

FIGS. 7B and 8B illustrate another alternate configuration. This linkagehas a better resistance to axial compression and disengagement.Referring to FIGS. 7B and 8B, the apex extends beyond closing portion 74and into an axial portion 79 which extends generally parallel to thelongitudinal axis of the graft. Provision of an axial extension 79provides a more secure enclosure for the aperture 77 as will be apparentto those of skill in the art. The embodiments of FIGS. 7B and 8B alsoillustrate an enclosed aperture 83 on the opposing apex. The aperture 83is formed by wrapping the apex in at least one complete revolution sothat a generally circumferentially extending portion 81 is provided.Circumferential portion 81 provides a stop, to limit axialcompressibility of the graft. The closed aperture 83 can be formed bywinding the wire of the apex about a mandrel either in the directionillustrated in FIG. 7B, or the direction illustrated in FIG. 7C. Theembodiment of FIG. 7C advantageously provided only a single wirethickness through the aperture 77, thereby minimizing the wall thicknessof the graft. This is accomplished by moving the crossover point outsideof the aperture 77, as will be apparent from FIG. 7C.

The link 70 in accordance with the present invention is preferablyformed integrally with the wire which forms the cage of the endovascularprosthesis. Alternatively, link 70 may be constructed from a separatematerial which is secured to the wire cage such as by soldering, suture,wrapping or the like.

The axial direction of the link 70 may also be varied, depending uponthe desired performance characteristics of the graft. For example, thedistal tips 76 of each link 70 may all face the same direction, such asproximal or distal with respect to the graft. See, for example, FIG. 5.Alternatively, one or more links in a given transverse plane of apexesmay face in a proximal direction, and one or more links in the sametransverse plane may face in the opposite direction. See, for example,FIG. 9.

Regardless of the axial orientation of the link 70, at least one andpreferably at least two links 70 are provided per transverse planeseparating adjacent graft segments. In an embodiment having six apexesper transverse plane, preferably at least two or three and in oneembodiment all six opposing apex pairs are provided with a link 70. SeeFIG. 5.

The distribution of the interlocking link 70 throughout the wire cagecan thus vary widely, depending upon the desired performancecharacteristics. For example, each opposing apex pair between adjacenttubular segments can be provided with a link 70. See FIG. 5.Alternatively, interlocking links 70 may be spaced circumferentiallyapart around the graft wall such as by positioning them at every secondor third opposing apex pair.

The distribution of the links 70 may also be varied along the axiallength of the graft. For example, a first zone at a proximal end of thegraft and a second zone at a distal end of the graft may be providedwith a relatively larger number of links 70 than a third zone in thecentral portion of the graft. In one embodiment, the transverse apexplane between the first and second tubular segments at the proximal endof the graft may be provided with a link 70 at each opposing apex pair.This has been determined by the present inventors to increase the radialstrength of the graft, which may be desirable at the proximal (superior)end of the graft and possibly also at the distal end of the graft whereresistance to leakage is an issue. A relatively lesser radial strengthmay be necessary in the central portion of the graft, where maintainingpatency of the lumen is the primary concern. For this reason, relativelyfewer links 70 may be utilized in a central zone, in an effort to simplygraft design as well as reduce collapse profile of the graft. See FIG.12.

In one straight segment graft, having four graft segments, threetransverse apex planes are provided. In the proximal apex plane, eachopposing pair of apexes is provided with a link 70. In the centraltransverse apex plane, three of the six apex pairs are provided with alinks 70, spaced apart at approximately 120°. Substantially equalcircumferential spacing of the link 70 is preferred, to providerelatively uniform resistance to bending regardless of graft position.The distal transverse apex plane may also be provided with a link 70 ateach opposing apex pair.

The foregoing interlocking link 70 in accordance with the presentinvention can be readily adapted to both the straight segment grafts asdiscussed above, as well as to the bifurcated grafts discussed below.

The interlocking link 70 can be utilized to connect any of a number ofindependent graft segments in axial alignment to produce either astraight segment or a bifurcation graft. The interlocking link 70 may beutilized as the sole means of securing adjacent segments to each other,or may be supplemented by additional attachment structures such as metalloops, sutures, welds and others which are well understood in the art.

Referring to FIGS. 12A through 12C there is illustrated a further wirelayout which allows a smaller collapsed profile for the vascular graft.In general, the embodiment of FIGS. 12A through 12C permits a series oflinks 70A and 70B to be staggered axially from one another as seen inFIGS. 12A and 12B. In this manner, adjacent links 70 do not lie in thesame transverse plane, and permit a tighter nesting of the collapsedwire cage. Preferably, between each adjoining graft segment, at least afirst group of links 70A is offset axially from a second group of links70B. In a six apex graft, having a link 70 at each apex, for example, afirst group of every other apex 70A may be positioned slightlyproximally of a second group of every other apex 70B. Referring to FIG.12C, this may be accomplished by extending an apex 76A by a d3 distancewhich is at least about 1.2 times and as large as 1.5 times or 2 timesor more the distance d2. The corresponding apexes 78 and 78A aresimilarly staggered axially, to produce the staggered interface betweenadjacent graft segments illustrated in FIG. 12A. Although a loop apex isillustrated in FIG. 12C as apex 78, any of the alternate apexesillustrated herein can be utilized in the staggered apex embodiment ofthe invention. The zig-zag pattern produced by axially offset links 70Aand 70B can reside in a pair of parallel transverse planes extendinggenerally between adjacent segments of the graft. Alternatively, thezig-zag relationship between adjacent links 70A and 70B can spiralaround the circumference of a graft in a helical pattern, as will beunderstood by those of skill in the art in view of the disclosureherein. The precise axial offset between adjacent staggered links 70Aand 70B can be optimized by one of ordinary skill in the art throughroutine experimentation, taking into account the desired physicalproperties and collapsed profile of the graft.

Referring to FIGS. 13 and 14, a straight segment deployment device andmethod in accordance with a preferred embodiment of the presentinvention are illustrated. A delivery catheter 80, having a dilator tip82, is advanced along guidewire 84 until the (anatomically) proximal end50 of the collapsed endoluminal vascular prosthesis 88 is positionedbetween the renal arteries 32 and 34 and the aneurysm 40. The collapsedprosthesis in accordance with the present invention has a diameter inthe range of about 2 to about 10 mm. Generally, the diameter of thecollapsed prosthesis is in the range of about 3 to 6 mm (12 to 18French). Preferably, the delivery catheter including the prosthesis willbe 16 F, or 15 F or 14 F or smaller.

The prosthesis 88 is maintained in its collapsed configuration by therestraining walls of the tubular delivery catheter 80, such that removalof this restraint would allow the prosthesis to self expand. Radiopaquemarker material may be incorporated into the delivery catheter 80,and/or the prosthesis 88, at least at both the proximal and distal ends,to facilitate monitoring of prosthesis position. The dilator tip 82 isbonded to an internal catheter core 92, as illustrated in FIG. 14, sothat the internal catheter core 92 and the partially expanded prosthesis88 are revealed as the outer sheath of the delivery catheter 80 isretracted.

As the outer sheath is retracted, the collapsed prosthesis 88 remainssubstantially fixed axially relative to the internal catheter core 92and consequently, self-expands at a predetermined vascular site asillustrated in FIG. 14. Continued retraction of the outer sheath resultsin complete deployment of the graft. After deployment, the expandedendoluminal vascular prosthesis 88 has radially self-expanded to adiameter anywhere in the range of about 20 to 40 mm, corresponding toexpansion ratios of about 1:2 to 1:20. In a preferred embodiment, theexpansion ratios range from about 1:4 to 1:8, more preferably from about1:4 to 1:6.

In addition to, or in place of, the outer sheath described above, theprosthesis 88 may be maintained in its collapsed configuration by arestraining lace, which may be woven through the prosthesis or wrappedaround the outside of the prosthesis in the collapsed reduced diameter.Following placement of the prosthesis at the treatment site, the lacecan be proximally retracted from the prosthesis thereby releasing it toself expand at the treatment site. The lace may comprise any of avariety of materials, such as sutures, strips of PTFE, FEP, polyesterfiber, and others as will be apparent to those of skill in the art inview of the disclosure herein. The restraining lace may extendproximally through a lumen in the delivery catheter or outside of thecatheter to a proximal control. The control may be a pull tab or ring,rotatable reel, slider switch or other structure for permitting proximalretraction of the lace. The lace may extend continuously throughout thelength of the catheter, or may be joined to another axially moveableelement such as a pull wire.

In general, the expanded diameter of the graft in accordance with thepresent invention can be any diameter useful for the intended lumen orhollow organ in which the graft is to be deployed. For most arterialvascular applications, the expanded size will be within the range offrom about 10 to about 40 mm. Abdominal aortic applications willgenerally require a graft having an expanded diameter within the rangeof from about 20 to about 28 mm, and, for example, a graft on the orderof about 45 mm may be useful in the thoracic artery. The foregoingdimensions refer to the expanded size of the graft in an unconstrainedconfiguration, such as on the table. In general, the graft will bepositioned within an artery having a slightly smaller interiorcross-section than the expanded size of the graft. This enables thegraft to maintain a slight positive pressure against the wall of theartery, to assist in retention of the graft during the period of timeprior to endothelialization of the polymeric sleeve 44.

The radial force exerted by the proximal segment 94 of the prosthesisagainst the walls of the aorta 30 provides a seal against the leakage ofblood around the vascular prosthesis and tends to prevent axialmigration of the deployed prosthesis. As discussed above, this radialforce can be modified as required through manipulation of various designparameters, including the axial length of the segment and the bendconfigurations. In another embodiment of the present invention, radialtension can be enhanced at the proximal, upstream end by increasing thethe wire gauge in the proximal zone. Wire diameter may range from about0.001 to 0.01 inches in the distal region to a range of from about 0.01to 0.03 inches in the proximal region.

An alternative embodiment of the wire layout which would cause theradial tension to progressively decrease from the proximal segments tothe distal segments, involves a progressive or step-wise decrease in thewire gauge throughout the entire wire support, from about 0.01 to 0.03inches at the proximal end to about 0.002 to 0.01 inches at the distalend. Such an embodiment, may be used to create a tapered prosthesis.Alternatively, the wire gauge may be thicker at both the proximal anddistal ends, in order to insure greater radial tension and thus, sealingcapacity. Thus, for instance, the wire gauge in the proximal and distalsegments may about 0.01 to 0.03 inches, whereas the intervening segmentsmay be constructed of thinner wire, in the range of about 0.001 to 0.01inches.

Referring to FIG. 15, there is illustrated two alternative deploymentsites for the endoluminal vascular prosthesis 42 of the presentinvention. For example, an aneurysm 33 is illustrated in the right renalartery 32. An expanded endoluminal vascular prosthesis 42, in accordancewith the present invention, is illustrated spanning that aneurysm 33.Similarly, an aneurysm 37 of the right common iliac 36 is shown, with aprosthesis 42 deployed to span the iliac aneurysm 37.

Referring to FIG. 16, there is illustrated a modified embodiment of theendovascular prosthesis 96 in accordance with the present invention. Inthe embodiment illustrated in FIG. 16, the endovascular prosthesis 96 isprovided with a wire cage 46 having six axially aligned segments 54. Aswith the previous embodiments, however, the endovascular prosthesis 96may be provided with anywhere from about 2 to about 10 or more axiallyspaced or adjacent segments 54, depending upon the clinical performanceobjectives of the particular embodiment.

The wire support 46 is provided with a tubular polymeric sleeve 44 ashas been discussed. In the present embodiment, however, one or morelateral perfusion ports or openings are provided in the polymeric sleeve44, such as a right renal artery perfusion port 98 and a left renalartery perfusion port 100 as illustrated.

Perfusion ports in the polymeric sleeve 44 may be desirable inembodiments of the endovascular prosthesis 96 in a variety of clinicalcontexts. For example, although FIGS. 1 and 16 illustrate a generallysymmetrical aneurysm 40 positioned within a linear infrarenal portion ofthe abdominal aorta, spaced axially apart both from bilaterallysymmetrical right and left renal arteries and bilaterally symmetricalright and left common iliacs, both the position and symmetry of theaneurysm 40 as well as the layout of the abdominal aortic architecturemay differ significantly from patient to patient. As a consequence, theendovascular prosthesis 96 may need to extend across one or both of therenal arteries in order to adequately anchor the endovascular prosthesis96 and/or span the aneurysm 40. The provision of one or more lateralperfusion ports or zones enables the endovascular prosthesis 96 to spanthe renal arteries while permitting perfusion therethrough, therebypreventing “stent jailing” of the renals. Lateral perfusion through theendovascular prosthesis 96 may also be provided, if desired, for avariety of other arteries including the second lumbar, testicular,inferior mesenteric, middle sacral, and alike as will be well understoodto those of skill in the art.

The endovascular prosthesis 96 is preferably provided with at least one,and preferably two or more radiopaque markers, to facilitate properpositioning of the prosthesis 96 within the artery. In an embodimenthaving perfusion ports 98 and 100 such as in the illustrated design, theprosthesis 96 should be properly aligned both axially and rotationally,thereby requiring the ability to visualize both the axial and rotationalposition of the device. Alternatively, provided that the deliverycatheter design exhibits sufficient torque transmission, the rotationalorientation of the graft may be coordinated with an indexed marker onthe proximal end of the catheter, so that the catheter may be rotatedand determined by an external indicium of rotational orientation to beappropriately aligned with the right and left renal arteries.

In an alternative embodiment, the polymeric sleeve 44 extends across theaneurysm 40, but terminates in the infrarenal zone. In this embodiment,a proximal zone 55 on the prosthesis 96 comprises a wire cage 46 but nopolymeric sleeve 44. In this embodiment, the prosthesis 96 stillaccomplishes the anchoring function across the renal arteries, yet doesnot materially interfere with renal perfusion. Thus, the polymericsleeve 44 may cover anywhere from about 50% to about 100% of the axiallength of the prosthesis 96 depending upon the desired length ofuncovered wire cage 46 such as for anchoring and/or lateral perfusionpurposes. In particular embodiments, the polymeric sleeve 44 may coverwithin the range of from about 70% to about 80%, and, in one foursegment embodiment having a single exposed segment, 75%, of the overalllength of the prosthesis 96. The uncovered wire cage 46 may reside atonly a single end of the prosthesis 96, such as for traversing the renalarteries. Alternatively, exposed portions of the wire cage 46 may beprovided at both ends of the prosthesis such as for anchoring purposes.

In a further alternative, a two part polymeric sleeve 44 is provided. Afirst distal part spans the aneurysm 40, and has a proximal end whichterminates distally of the renal arteries. A second, proximal part ofthe polymeric sleeve 44 is carried by the proximal portion of the wirecage 46 which is positioned superiorly of the renal arteries. Thisleaves an annular lateral flow path through the side wall of thevascular prosthesis 96, which can be axially aligned with the renalarteries, without regard to rotational orientation.

The axial length of the gap between the proximal and distal segments ofpolymeric sleeve 44 can be adjusted, depending upon the anticipatedcross-sectional size of the ostium of the renal artery, as well as thepotential axial misalignment between the right and left renal arteries.Although the right renal artery 32 and left renal artery 34 areillustrated in FIG. 16 as being concentrically disposed on oppositesides of the abdominal aorta, the take off point for the right or leftrenal arteries from the abdominal aorta may be spaced apart along theabdominal aorta as will be familiar to those of skill in the art. Ingeneral, the diameter of the ostium of the renal artery measured in theaxial direction along the abdominal aorta falls within the range of fromabout 7 mm to about 20 mm for a typical adult patient.

Prior art procedures presently use a 7 mm introducer (18 French) whichinvolves a surgical procedure for introduction of the graft deliverydevice. Embodiments of the present invention can be constructed having a16 French or 15 French or 14 French or smaller profile (e.g. 3-4 mm)thereby enabling placement of the endoluminal vascular prosthesis of thepresent invention by way of a percutaneous procedure. In addition, theendoluminal vascular prosthesis of the present invention does notrequire a post implantation balloon dilatation, can be constructed tohave minimal axial shrinkage upon radial expansion.

Referring to FIG. 17, there is disclosed a schematic representation ofthe abdominal part of the aorta and its principal branches as in FIG. 1.An expanded bifurcated endoluminal vascular prosthesis 102, inaccordance with the present invention, is illustrated spanning theaneurysms 103, 104 and 105. The endoluminal vascular prosthesis 102includes a polymeric sleeve 106 and a tubular wire support 107, whichare illustrated in situ in FIG. 17. The sleeve 106 and wire support 107are more readily visualized in the exploded view shown in FIG. 19. Theendoluminal prosthesis 102 illustrated and described herein depicts anembodiment in which the polymeric sleeve 106 is situated concentricallyoutside of the tubular wire support 107. However, other embodiments mayinclude a sleeve situated instead concentrically inside the wire supportor on both of the inside and the outside of the wire support.Alternatively, the wire support may be embedded within a polymericmatrix which makes up the sleeve. Regardless of whether the sleeve 106is inside or outside the wire support 107, the sleeve may be attached tothe wire support by any of a variety of means, as has been previouslydiscussed.

The tubular wire support 107 comprises a primary component 108 fortraversing the aorta and a first iliac, and a branch component 109 forextending into the second iliac. The primary component 108 may be formedfrom a continuous single length of wire, throughout both the aorta trunkportion and the iliac branch portion. See FIGS. 19 and 20.Alternatively, each iliac branch component can be formed separately fromthe aorta trunk portion. Construction of the graft from a three partcage conveniently facilitates the use of different gauge wire in thedifferent components (e.g. 14 gauge main trunk and 10 gauge branchcomponents).

The wire support 107 is preferably formed in a plurality of discretesegments, connected together and oriented about a common axis. In FIG.20, Section A corresponds to the aorta trunk portion of the primarycomponent 108, and includes segments 1-5. Segments 6-8 (Section B)correspond to the iliac branch portion of the primary component 108.

In general, each of the components of the tubular wire support 107 canbe varied considerably in diameter, length, and expansion coefficient,depending upon the intended application. For implantation within atypical adult, the aorta trunk portion (section A) of primary component108 will have a length within the range of from about 5 cm to about 12cm, and, typically within the range of from about 9 cm to about 10 cm.The unconstrained outside expanded diameter of the section A portion ofthe primary component 108 will typically be within the range of fromabout 20 mm to about 40 mm. The unconstrained expanded outside diameterof the section A portion of primary component 108 can be constant orsubstantially constant throughout the length of section A, or can betapered from a relatively larger diameter at the proximal end to arelatively smaller diameter at the bifurcation. In general, the diameterof the distal end of section A will be on the order of no more thanabout 95% and, preferably, no more than about 85% of the diameter of theproximal end of section A.

The right and left iliac portions, corresponding to section B on primarycomponent 108 and section C will typically be bilaterally symmetrical.Section C length will generally be within the range of from about 1 cmto about 5 cm, and section C diameter will typically be within the rangeof from about 10 mm to about 20 mm.

Referring to FIG. 19, the wire cage 107 is dividable into a proximalzone 110, a central zone 111 and a distal zone 112. As has beendiscussed, the wire cage 107 can be configured to taper from arelatively larger diameter in the proximal zone 110 to a relativelysmaller diameter in the distal zone 112. In addition, the wire cage 107can have a transitional tapered and or stepped diameter within a givenzone.

The wire may be made from any of a variety of different alloys and wirediameters or nonround cross-sections, as has been discussed. In oneembodiment of the bifurcation graft, the wire gauge remainssubstantially constant throughout section A of the primary component 49and steps down to a second, smaller cross-section throughout section Bof primary component 108.

A wire diameter of approximately 0.018 inches may be useful in the aortatrunk portion of a graft having five segments each having 2.0 cm lengthper segment, each segment having six struts intended for use in theaorta, while a smaller diameter such as 0.012 inches might be useful forsegments of the graft having 6 struts per segment intended for the iliacartery.

In one embodiment of the present invention, the wire diameter may betapered throughout from the proximal to distal ends of the section Aand/or section B portions of the primary component 108. Alternatively,the wire diameter may be tapered incremental or stepped down, or steppedup, depending on the radial strength requirements of each particularclinical application. In one embodiment, intended for the abdominalaortic artery, the wire has a cross-section of about 0.018 inches in theproximal zone 110 and the wire tapers down regularly or in one or moresteps to a diameter of about 0.012 inches in the distal zone 112 of thegraft 102. End point dimensions and rates of taper can be varied widely,within the spirit of the present invention, depending upon the desiredclinical performance.

In general, in the tapered or stepped wire embodiments, the diameter ofthe wire in the iliac branches is no more than about 80% of the diameterof the wire in the aortic trunk. This permits increased flexibility ofthe graft in the region of the iliac branches, which has been determinedby the present inventors to be clinically desirable.

Referring to FIG. 20, there is illustrated a plan view of the singleformed wire used for rolling about a longitudinal axis to produce aprimary segment 108 having a five segment aorta section and a threesegment iliac section. The formed wire exhibits distinct segments, eachcorresponding to an individual tubular segment in the tubular support.Additional details of the wire cage layout and construction can be foundin copending U.S. patent application Ser. No. 09/034,689 entitledEndoluminal Vascular Prosthesis, filed Mar. 4, 1998, the disclosure ofwhich is incorporated in its entirety herein by reference.

Each segment has a repeating pattern of proximal bends 60 connected tocorresponding distal bends 62 by wall sections 64 which extend in agenerally zig zag configuration when the segment is radially expanded,as has been discussed in connection with FIG. 3. Each segment isconnected to the adjacent segment through a connector 66, and one ormore links 70 as has been discussed in connection with FIGS. 5-12. Theconnector 66 in the illustrated embodiment comprises two wall sections64 which connect a proximal bend 60 on a first segment with a distalbend 62 on a second, adjacent segment. The connector 66 may additionallybe provided with a connector bend 68, which may be used to impartincreased radial strength to the graft and/or provide a tie site for acircumferentially extending suture.

In the illustrated embodiment, section A is intended for deploymentwithin the aorta whereas section B is intended to be deployed within afirst iliac. Thus, section B will preferably have a smaller expandeddiameter than section A. This may be accomplished by providing fewerproximal and distal bends 60, 62 per segment in section B or in othermanners as will be apparent to those of skill in the art in view of thedisclosure herein. In the illustrated embodiment, section B has onefewer proximal bend 60 per segment than does each segment in section A.This facilitates wrapping of the wire into a tubular prosthesis cagesuch as that illustrated in FIG. 19, so that the iliac branch has asmaller diameter than the aorta branch. At the bifurcation, an openingremains for connection of the second iliac branch. The second branch ispreferably formed from a section of wire in accordance with the generalprinciples discussed above, and in a manner that produces a similarlydimensioned wire cage as that produced by section B. The second iliacbranch (section C) may be attached at the bifurcation to section Aand/or section B in any of a variety of manners, to provide a securejunction therebetween. In one embodiment, one or two of the proximalbends 60 on section C will be secured to the corresponding distal bends62 on the distal most segment of section A. Attachment may beaccomplished such as through the use of a circumferentially threadedsuture, through links 70 as has been discussed previously, throughsoldering or other attachment means. The attachment means will beinfluenced by the desirable flexibility of the graft at the bifurcation,which will in turn be influenced by the method of deployment of thevascular graft as will be apparent to those of skill in the art in viewof the disclosure herein.

The collapsed prosthesis in accordance with the present invention has adiameter in the range of about 2 to about 10 mm. Preferably, the maximumdiameter of the collapsed prosthesis is in the range of about 3 to 6 mm(12 to 18 French). Some embodiments of the delivery catheter includingthe prosthesis will be in the range of from 18 to 20 or 21 French; otherembodiments will be as low as 19 F, 16 F, 14 F, or smaller. Afterdeployment, the expanded endoluminal vascular prosthesis has radiallyself-expanded to a diameter anywhere in the range of about 20 to 40 mm,corresponding to expansion ratios of about 1:2 to 1:20. In a preferredembodiment, the expansion ratios range from about 1:4 to 1:8, morepreferably from about 1:4 to 1:6.

The self expandable bifurcation graft of the present invention can bedeployed at a treatment site in accordance with any of a variety oftechniques as will be apparent to those of skill in the art. One suchtechnique is disclosed in copending patent application Ser. No.08/802,478 entitled Bifurcated Vascular Graft and Method and Apparatusfor Deploying Same, filed Feb. 20, 1997, the disclosure of which isincorporated in its entirety herein by reference.

A partial cross-sectional side elevational view of one deploymentapparatus 120 in accordance with the present invention is shown in FIG.21. The deployment apparatus 120 comprises an elongate flexiblemulticomponent tubular body 122 having a proximal end 124 and a distalend 126. The tubular body 122 and other components of this system can bemanufactured in accordance with any of a variety of techniques wellknown in the catheter manufacturing field. Suitable materials anddimensions can be readily selected taking into account the naturalanatomical dimensions in the iliacs and aorta, together with thedimensions of the desired percutaneous access site.

The elongate flexible tubular body 122 comprises an outer sheath 128which is axially movably positioned upon an intermediate tube 130. Acentral tubular core 132 is axially movably positioned within theintermediate tube 130. In one embodiment, the outer tubular sheathcomprises extruded PTFE, having an outside diameter of about 0.250″ andan inside diameter of about 0.230″. The tubular sheath 128 is providedat its proximal end with a manifold 134, having a hemostatic valve 136thereon and access ports such as for the infusion of drugs or contrastmedia as will be understood by those of skill in the art.

The outer tubular sheath 128 has an axial length within the range offrom about 40″ to about 55″, and, in one embodiment of the deploymentdevice 120 having an overall length of 110 cm, the axial length of theouter tubular sheath 128 is about 52 cm and the outside diameter is nomore than about 0.250″. Thus, the distal end of the tubular sheath 128is located at least about 16 cm proximally of the distal end 126 of thedeployment catheter 120 in stent loaded configuration.

As can be seen from FIGS. 22 and 25-26, proximal retraction of the outersheath 128 with respect to the intermediate tube 130 will expose thecompressed iliac branches of the graft, as will be discussed in moredetail below.

A distal segment of the deployment catheter 120 comprises an outertubular housing 138, which terminates distally in an elongate flexibletapered distal tip 140. The distal housing 138 and tip 140 are axiallyimmovably connected to the central core 132 at a connection 142.

The distal tip 140 preferably tapers from an outside diameter of about0.225″ at its proximal end to an outside diameter of about 0.070″ at thedistal end thereof. The overall length of the distal tip 140 in oneembodiment of the deployment catheter 120 is about 3″. However, thelength and rate of taper of the distal tip 140 can be varied dependingupon the desired trackability and flexibility characteristics. Thedistal end of the housing 138 is secured to the proximal end of thedistal tip 140 such as by thermal bonding, adhesive bonding, and/or anyof a variety of other securing techniques known in the art. The proximalend of distal tip 140 is preferably also directly or indirectlyconnected to the central core 132 such as by a friction fit and/oradhesive bonding.

In at least the distal section of the catheter, the central core 132preferably comprises a length of hypodermic needle tubing. Thehypodermic needle tubing may extend throughout the length catheter tothe proximal end thereof, or may be secured to the distal end of aproximal extrusion as illustrated for example in FIG. 22. A centralguidewire lumen 144 extends throughout the length of the tubular centralcore 132, having a distal exit port 146 and a proximal access port 148as will be understood by those of skill in the art.

Referring to FIGS. 22-24, a bifurcated endoluminal graft 150 isillustrated in a compressed configuration within the deployment catheter120. The graft 150 comprises a distal aortic section 152, a proximalipsilateral iliac portion 154, and a proximal contralateral iliacportion 156. The aortic trunk portion 152 of the graft 150 is containedwithin the tubular housing 138. Distal axial advancement of the centraltubular core 132 will cause the distal tip 140 and housing 138 toadvance distally with respect to the graft 150, thereby permitting theaortic trunk portion 152 of the graft 150 to expand to its larger,unconstrained diameter. Distal travel of the graft 150 is prevented by adistal stop 158 which is axially immovably connected to the intermediatetube 130. Distal stop 158 may comprise any of a variety of structures,such as an annular flange or component which is adhered to, bonded to orintregally formed with a tubular extension 160 of the intermediate tube132. Tubular extension 160 is axially movably positioned over thehypotube central core 132.

The tubular extension 160 extends axially throughout the length of thegraft 150. At the proximal end of the graft 150, a step 159 axiallyimmovably connects the tubular extension 160 to the intermediate tube130. In addition, the step 159 provides a proximal stop surface toprevent proximal travel of the graft 150 on the catheter 120. Thefunction of step 159 can be accomplished through any of a variety ofstructures as will be apparent to those of skill in the art in view ofthe disclosure herein. For example, the step 159 may comprise an annularring or spacer which receives the tubular extension 160 at a centralaperture therethrough, and fits within the distal end of theintermediate tube 130. Alternatively, the intermediate tube 130 can bereduced in diameter through a generally conical section or shoulder tothe diameter of tubular extension 160.

Proximal retraction of the outer sheath 128 will release the iliacbranches 154 and 156 of the graft 150. The iliac branches 154 and 156will remain compressed, within a first (ipsilateral) tubular sheath 162and a second (contralateral) tubular sheath 164. The first tubularsheath 162 is configured to restrain the ipsilateral branch of the graft150 in the constrained configuration, for implantation at the treatmentsite. The first tubular sheath 162 is adapted to be axially proximallyremoved from the iliac branch, thereby permitting the branch to expandto its implanted configuration. In one embodiment, the first tubularsheath 162 comprises a thin walled PTFE extrusion having an outsidediameter of about 0.215″ and an axial length of about 7.5 cm. A proximalend of the tubular sheath 162 is necked down such as by heat shrinkingto secure the first tubular sheath 162 to the tubular extension 160. Inthis manner, proximal withdrawal of the intermediate tube 130 will inturn proximally advance the first tubular sheath 162 relative to thegraft 150, thereby deploying the self expandable iliac branch of thegraft 150.

The second tubular sheath 164 is secured to the contralateral guidewire166, which extends outside of the tubular body 122 at a point 168, suchas may be conveniently provided at the junction between the outertubular sheath 128 and the distal housing 138. The second tubular sheath164 is adapted to restrain the contralateral branch of the graft 150 inthe reduced profile. In one embodiment of the invention, the secondtubular sheath 164 has an outside diameter of about 0.215″ and an axiallength of about 7.5 cm. The second tubular sheath 164 can have asignificantly smaller cross-section than the first tubular sheath 162,due to the presence of the tubular core 132 and intermediate tube 130within the first iliac branch 154.

The second tubular sheath 164 is secured at its proximal end to a distalend of the contralateral guidewire 166. This may be accomplished throughany of a variety of securing techniques, such as heat shrinking,adhesives, mechanical interfit and the like. In one embodiment, theguidewire is provided with a knot or other diameter enlarging structureto provide an interference fit with the proximal end of the secondtubular sheath 156, and the proximal end of the second tubular sheath156 is heat shrunk and/or bonded in the area of the knot to provide asecure connection. Any of a variety of other techniques for providing asecure connection between the contralateral guidewire 166 and tubularsheath 156 can readily be used in the context of the present inventionas will be apparent to those of skill in the art in view of thedisclosure herein. The contralateral guidewire 166 can comprise any of avariety of structures, including polymeric monofilament materials,braided or woven materials, metal ribbon or wire, or conventionalguidewires as are well known in the art.

In use, the free end of the contralateral guidewire 166 ispercutaneously inserted into the arterial system, such as at a firstpuncture in a femoral artery. The contralateral guidewire is advancedthrough the corresponding iliac towards the aorta, and crossed over intothe contralateral iliac in accordance with cross over techniques whichare well known in the art. The contralateral guidewire is then advanceddistally down the contralateral iliac where it exits the body at asecond percutaneous puncture site.

The deployment catheter 120 is thereafter percutaneously inserted intothe first puncture, and advanced along a guidewire (e.g. 0.035 inch)through the ipsilateral iliac and into the aorta. As the deploymentcatheter 120 is transluminally advanced, slack produced in thecontralateral guidewire 166 is taken up by proximally withdrawing theguidewire 166 from the second percutaneous access site. In this manner,the deployment catheter 120 is positioned in the manner generallyillustrated in FIG. 25.

Referring to FIG. 26, the outer sheath 128 is proximally withdrawn whilemaintaining the axial position of the overall deployment catheter 120,thereby releasing the first and second iliac branches of the graft 150.Proximal advancement of the deployment catheter 120 and contralateralguidewire 166 can then be accomplished, to position the iliac branchesof the graft 150 within the iliac arteries as illustrated.

Referring to FIG. 27, the central core 132 is distally advanced therebydistally advancing the distal housing 138 as has been discussed. Thisexposes the aortic trunk of the graft 150, which deploys into its fullyexpanded configuration within the aorta. As illustrated in FIG. 28, thecontralateral guidewire 166 is thereafter proximally withdrawn, therebyby proximally withdrawing the second sheath 164 from the contralateraliliac branch 156 of the graft 150. The contralateral branch 156 of thegraft 150 thereafter self expands to fit within the iliac artery. Theguidewire 166 and sheath 164 may thereafter be proximally withdrawn andremoved from the patient, by way of the second percutaneous access site.

Thereafter, the deployment catheter 120 may be proximally withdrawn torelease the ipsilateral branch 154 of the graft 150 from the firsttubular sheath 162. Following deployment of the ipsilateral branch 154of the prosthesis 150, a central lumen through the aortic trunk 152 andipsilateral branch 154 is sufficiently large to permit proximalretraction of the deployment catheter 120 through the deployedbifurcated graft 150. The deployment catheter 120 may thereafter beproximally withdrawn from the patient by way of the first percutaneousaccess site.

While a number of preferred embodiments of the invention and variationsthereof have been described in detail, other modifications and methodsof using and medical applications for the same will be apparent to thoseof skill in the art. Accordingly, it should be understood that variousapplications, modifications, and substitutions may be made ofequivalents without departing from the spirit of the invention or thescope of the claims.

What is claimed is:
 1. A method of making an endoluminal prosthesis,comprising the steps of: providing a length of wire; forming the wireinto at least two zig-zag sections having proximal and distal apexes;rolling the formed wire about an axis to produce at least two tubularelements positioned along the axis such that at least one proximal apexon one element axially overlaps with a distal apex on a second element;folding one of the proximal or distal apex through the overlappingproximal or distal apex to produce a folded link; and closing the foldedlink such that the folded apex forms a functionally closed aperturewhich substantially entraps the overlapping apex.
 2. A method as inclaim 1, further comprising the step of positioning a tubular polymericsleeve concentrically on at least one of the tubular elements.
 3. Amethod as in claim 2, wherein the positioning step comprises positioningthe tubular polymeric sleeve concentrically on the outside surface ofthe tubular element.
 4. A method as in claim 3, wherein the tubularpolymeric sleeve comprises PTFE.
 5. A movable link for securing twoportions of the wall of a tubular endovascular prosthesis, comprising: afirst wire portion having two side-by-side legs and an apex thereon; anda second wire portion adjacent the first wire portion; wherein the firstwire portion is wrapped around the second wire portion to form afunctionally closed aperture, wherein the second wire portion issubstantially entrapped within the aperture.